The haze consists mainly of sulphur and nitrogen compounds (as a gas, fine liquid or solid particles called aerosols) with naturally occurring substances like sea salt, wildfire ash and windblown soil dust. The longer sulphur and nitrogen compounds remain in the atmosphere, the greater chance they have to transform into acids similar to ACID RAIN. Arctic haze also carries a mess of airborne toxic contaminants (eg, herbicides and pesticides such as lindane and DDT); heavy metals (eg, lead, mercury and vanadium); and industrial organic compounds (eg, solvents, DIOXINS and PCBs).
The haze blankets virtually the entire area north of 60° lat. Concentrations tend to reach a maximum near the top of the inversion layer (400-800 m above ground) and decrease above it. Arctic pollution levels are also generally 10-20 times higher than those over Antarctica and 10 times greater than over nonindustrial areas of North America.
The High Arctic is 20-40 times more polluted in winter than in summer. From February-May, there are enough particles suspended in the air to become visible as a haze. During the summer the pollution haze vanishes. There are at least 3 reasons why this occurs: wintertime inversions form invisible barriers through which accumulated pollution cannot escape; large weather systems that control the movement of pollutants into, through and out of the Arctic are quite vigorous in winter and usually have a northward flow; and in winter, the air passes over what is essentially a frozen desert, so there is little rain or snow to wash out pollutants.